Do you think it's appropriate to take photographs in a cemetery?

My mother and I are going to visit the cemeteries tonight and I was thinking of bringing the camera. Then I started to wonder about cemetery etiquette - is it OK to take pictures at/of a cemetery?
I know it would be inappropriate to snap away with a funeral in progress but this will be later in the evening and I really just wanted to take pictures of the headstones/markers belonging to our family. Some of them are getting quite ancient and they wont be around for that much longer, I would really like to immortalize them.
Also, do you think it's OK to take scenery pictures of a cemetery? They're beautiful and make for interesting photography but do you feel it's respectful and appropriate?